1. Field of the Invention
The present invention relates to a limited slip differential gear employed by a vehicle, more particularly to a limited slip differential gear that is small in size, simple in construction and light in weight compared with a conventional limited slip differential gear.
2. Prior Art
A so-called limited slip differential gear (hereinafter referred as simply LSD) has been conventionally employed by a vehicle so that the vehicle can pull itself out of the mud when one wheel was got stuck in the mud or preventing swerving phenomenon when the vehicle turns.
There is known an LSD of this type, for example, as illustrated in FIG. 8 of Japanese Utility Model Registration No. 3001939.
FIG. 8 schematically shows a cross section of the LSD. In an LSD 01, a ring gear 04 meshing with a drive pinion 02 is fixed to differential gear cases (simply referred to as gear cases) 06a and 06b.
When a driving force of an engine, not shown, is transmitted to the drive pinion 02, the entire gear cases are turned.
A pair of side gears 010a and 010b to be connected with wheel axles 08a and 08b are provided in the gear cases 06a and 06b.
Pinion gears 012a and 012b mesh with each other and turn between the side gears 010a and 010b. Multiple disc clutch mechanisms 024a and 024b are interposed between the gear cases 06a and 06b and the side gears 010a and 010b, wherein they are pressed against each other when a pair of pressure rings 018a and 018b are moved in the axial outward direction so as to limit the differential motion of the side gears 010a and 010b.
The pinion gears 012a and 012b are respectively journaled by pinion shaft ends 016 that protrude vertically in four directions relative to a cross pinion shaft 014. The pinion shaft ends 016 are freely engageably supported and held by the pair of pressure rings 018a and 018b. Cam surfaces, not shown, are formed on both sides of these pinion shaft ends 016, and they can be retained by cam surfaces formed on the tip end portion of the pressure rings 018a and 018b at the surfaces where the cam surfaces formed on the pinion shaft ends 016 confront and contact those formed on the pressure rings 018a and 018b.
Meanwhile, weight reduction of a chassis has been conventionally required to improve fuel economy, and so forth of a car. Particularly, in a racing car, and so forth, the weight reduction of the chassis has been strongly required in view of high speed of a car and an operability of a steering wheel. Accordingly, it has been an important object to reduce the weight of each unit section employed by the car of this type as much as possible. Meanwhile, in the conventional LSD having the construction set forth above, the number of parts of each unit is large, and hence there remains a problem in respect of capacity and weight of the car.